The present invention relates generally to the curing of vehicle tires and similar vulcanized products.
More particularly, the invention relates to the shaping and curing of such tires and products in presses or molds having insertable bladders, tubes, bags, or bladderless center mechanisms into which high temperature water is introduced for shaping, curing, and molding, after which cold water is introduced for final cooling and shaping.
More specifically, this invention relates to a method, and associated apparatus and systems, to achieve substantial conservation of energy in such curing processes.
In the manufacture of vehicle tires and similar vulcanized products (e.g., air springs, curing bladders, etc.) the modern practice in the art of shaping and curing the same has been to insert a bladder, tube or air bag into an uncured band or barrel-shaped tire or product; to supply pressure to the interior of the inserted member while closing separable mold pieces around the assemblage to form the tire or product into its desired toroidal or other finished shape; and, thereafter, to supply heat to the mold parts by a platen or autoclave or pot heater, while supplying vulcanizing heat and shaping and molding pressure to the interior of the inserted bladder member for the prescribed time. In recent years, the widespread practice in the industry and art has been to use automatic tire shaping and curing presses such as the type known by the trademark "Bag-O-Matic" manufactured by the McNeil Corp. of Akron, Ohio, and the type known by the trademark "Autoform" manufactured by NRM Corp. of Akron, Ohio. These types of automatic presses, which are well-known in the art and industry, generally employ separable mold halves with center shaping and curing mechanisms utilizing bladders into which shaping, heating, and cooling gases, fluids or media are introduced for the shaping, molding and curing of the tires.
Recently, the principal shaping and curing fluid or medium utilized in the process has been high pressure and high temperature hot water. The conventional technique for employing this hot water curing process generally comprises the steps of: (1) closing the mold and starting shaping; (2) flushing the shaping fluid; (3) circulating high pressure hot water; (4) flushing the hot water with high pressure cold water and thereafter circulating it for cooling and shaping; and (5) draining the internal water and creating an internal vacuum as the molds open for extraction of the tire.
It will be readily appreciated by those skilled in the art that there is a substantial energy loss between steps three and four by virtue of the mixing of the hot water with cold, especially as such processes and systems are usually closed and are dependent upon the most efficient reuse of the shaping and curing fluids.
For a more detailed description of this state of the art of hot water curing, reference may be made to an article entitled "Successful Use of HTHW For Tire Curing Relies On Water Treatment, Recovery" in the journal "Heating, Piping & Air Conditioning" of March, 1963, at pages 110 through 116.